Geomorphology of the Galicia Bank Region (NW Iberian Peninsula)

Abstract

Multibeam bathymetry has been used to study in detail the morphology of the Galicia Bank region (< 700 m down to 5200 m water depth), in the NW Iberian Margin. Five physiographic provinces displaying a complex morphology have been defined. Their geomorphology is characterized by three types of features based on their origin: tectonic, sedimentary and oceanographic. Tectonic features are dominant, comprise fault scarps (normal and inverse) and highs. They condition the general geometry and morphology of the provinces. Sedimentary features (erosive and depositional) are mainly related to tectonic features, both their location and genesis. The erosive features comprise slide scars, gullies, channels, and main channels. The valleys eroding the provinces form turbidity systems that drain radially the region of the Galicia Bank, transporting the sediment toward the Biscay and Iberian abyssal plains. The depositional features comprise slides and wedges and lobes formed by mass-movement deposits; also, coral bioconstructions appear locally associated to the structural highs. All these features and the erosive ones are mostly the product of the faulted flank and structural high activity and erosion by mass wasting, and of the steep gradients (1 to 50º) of the Region. The oceanographic features comprise contourites (moat associated to drifts and sediment wave fields) and sediment wave fields. Their development is conditioned and favoured by the action of bottom currents.